Nearly 200,000 hip replacements are performed each year in the United States and the number is expected to continue to grow as the population ages. The usual reasons for hip replacement are osteoarthritis, rheumatoid arthritis and traumatic arthritis, all of which can cause pain and stiffness that limit mobility and the ability to perform daily living activities. Hip replacement surgery is usually performed when other measures (e.g., physical therapy, medications, and walking aids) are unable to overcome the chronic pain and disability associated with these conditions.
Various techniques are used by orthopedic surgeons to perform hip replacements. These include the following approaches: anterior, antero-lateral, posterior, and posterolateral. The posterior and posteolateral approaches account for approximately 60% to 70% of hip replacement surgeries.
Traditional hip replacement surgery involves the use of a reamer to remove bone and tissue from the acetabulum. During a typical procedure, a reamer is attached to the distal end of a spindle that provides articulation to the device. A coupling located at the spindle distal end facilitates connection of the reamer thereto. Traditional couplings are generally constructed of a bayonet design in which the coupling must be physically manipulated to attach the reamer to the distal end of a spindle. Typically, these prior art couplings require the operator to physically manipulate the coupling mechanism to attach and detach an orthopedic cutting tool, such as a reamer. Manipulation of prior art coupling mechanisms typically require the use of the hands to attach and detach the cutting tool.
Such manipulation of the attachment coupling mechanism is not ideal because physical contact of the coupling and cutting tool could cause either or both of the coupling and the tool to become contaminated. Thus, minimizing physical contact of the coupling and the cutting tool is ideal. Furthermore, physical manipulation of the coupling mechanism hinders a physician's ability to manipulate other devices simultaneously. A multitude of reamers are typically used during a hip replacement surgical procedure to prepare the acetabulum to receive a prosthetic cup. Use of prior art couplings would require each reamer to be physically attached and removed. Thus, it would be much easier and less cumbersome if the operator did not have to physically manipulate the coupling mechanism to attach a cutting tool.
The present invention, therefore, provides a coupling mechanism that does not require physical manipulation to connect an orthopedic cutting tool, such as a reamer, to a spindle or shaft. The coupling mechanism of the present invention is designed to attach an orthopedic cutting tool to the end of a spindle by physical contact of the cutting tool with that of the mechanism.
The coupling mechanism comprises an arrangement of a plurality of slots, each slot having an angled geometry and orientation that are designed to align and secure a cutting tool therewithin. The arrangement and angled geometry of the various slots within the mechanism encourages the engagement of a cross bar driver interface within the coupling. A bias member incorporated within the mechanism provides a bias force that causes the plurality of slots to align, thereby securing the driver interface therewithin. Thus, a cutting tool can be attached to the end of a spindle by physical contact of the driver interface of the tool with the coupling mechanism, thus eliminating the need to manipulate the mechanism by hand.